McCormack will help the Office of the Prosecutor develop a solid understanding of complex legal issues and will provide advice on the application and interpretation of international humanitarian law, in relation to crimes within the jurisdiction of the Court.

ICC Prosecutor Moreno-Ocampo said McCormack has a worldwide reputation for his scholarship and expertise in international humanitarian law. "He combines deep knowledge of the law with how it has been applied in military operations," Moreno-Ocampo said.

McCormack said the position will help him further his work in the specialised area of international humanitarian law.

"The Prosecutor is now offering me the opportunity to become involved in the very process I have argued for and I cannot, in good conscience, do anything but enthusiastically embrace the opportunity he has created for me," he said.

McCormack has acted as an adviser on international law matters before the International Criminal Tribunal for the former Yugoslavia - for the trial of Slobodan Milosevic - and provided expert Law of War advice for the defence of David Hicks before the US Military Commission in Guantanamo Bay.